What is Chaos Draft?
Chaos draft is a regular draft, but simply put, each player is given three boosters at random from all (or part of) of magic’s history; they then draft these and battle each other in a (swiss or single elimination) 
tournament with these decks.
How random do these have to be?
How you choose to run your chaos draft is up to you, but there are a couple of different techniques as recommendations-
- Using all of the available 24 boosters assigned, plus the prize support (Ideally random boosters for the cool factor, but that will depend on your TO) just shuffle together and hand out three to each player.
- Use the available boosters, but ask the players for preference of some of the boosters. For example, it is commonplace at Grand Prixs to have a revised booster as a prize as opposed to one of the random 24 opened, and some player groups may dislike using silver boarded cards in their drafts.
- Use your knowledge to have piles of roughly equal ‘value’ in how interesting they will be to players, and distribute these randomly. This option does prevent the negative player experience of being handed the unfortunate pile of three standard legal sets, but this does take time and prevents the piles from being strictly ‘random’.
Some hints to help running or judging a Chaos Draft
-Some of the older cards may have had errata changes since being printed, especially where creature types are concerned. If you are asked what an old card does, make sure to check the current oracle wording rather than just going by what the card says, as in some cases there have even been functional errata changes that can change how a card works, such as Loxodon Warhammer.
-If you’re using boosters with different sizes, it’s good practice to remind players not to worry if they have slightly less cards than others, this’ll happen when there are booster pack sizes ranging from 8-15! (For example Fallen Empires boosters only have 8 cards. Unglued, only 10 cards.)
-Even if some of the older and more exotic boosters are harder to get ahold of, players will often appreciate paying slightly more for the opportunity to play with rarer sets with cards they may never have seen before! A special mention to booster packs such as the mirrodin besieged prerelease packs that cannot really be obtained or played with commercially, a chaos draft is the perfect spot to crack them and enjoy.
-If being run as a non pickup event, swiss format is much preferred over single elimination – people entering your chaos draft are rarely the most competitive of the bunch.
-Ensure that your players there are having fun: ask the player with the unhinged pack what sweet wacky rare he cracked. Ask the future sight booster player if he won the ‘goyf lottery.
-Share in the misery of the poor individual unfortunate enough to have the homelands booster(s) placed in his lap. Fun is the key principle, and everything you can do as a judge to enhance that is welcomed!
-It’s also recommended to make a brief mention that people should expect to draft slower than usual, as most people will be reading some of the cards for the first time, so avoiding a pile up works best for everyone.
-Finally, chaos draft is a great place for you as a judge to hone your skills on some of the more obscure facets of the rules. For instance, banding is alive and well in some of the old sets, and some of the rules interactions that come up between cards can take some careful interpretation of the rules.
Happy drafting, judges, and hope you find some sweet boosters to be wacky with!